Fig. 4.

Effects of M. alba stem extract (MSE), oxyresveratrol (OXY), glucosamine sulfate (GS) and diclofenac sodium (DCS) on IL-1β-induced PGE₂ production (A) and COX-2 protein expression (B) in the C28/I2 human chondrocyte cell line. The cells were untreated (Bar 1), only stimulated with IL-1β 10 ng/mL (Bar 2) and pretreated with various concentrations of MSE and OXY as well as GS 10 μg/mL and DCS 10 μg/mL for 2 h and then stimulated by 10 ng/mL IL-1β for 22 h. The cell culture supernatant was collected and determined the PGE₂ production by using ELISA kit. The concentration of PGE₂ was normalized to the activated control. The expression of COX-2 (72 kDa) was determined by western blotting analysis and GAPDH protein (38 kDa) was used as a loading control. The data are expressed as mean ± S.D. of three independent experiments. **p < 0.01 compared to the IL-1β-stimulated cells.